1. Field of the Invention
The present invention relates to a detecting method, a detecting device, and a projecting device.
2. Description of the Related Art
A projecting device which reflects light from a light source by a reflective light modulator to modulate based on image data and selectively reflects the modulated light by a reflective polarization plate to project an image on a projected medium is known. In such projecting device, it is possible to stabilize a light amount of the light source by detecting the light amount of the light source by an optical sensor arranged on an optical path of the light emitted from the light source to feedback-control the light source based on the detected light amount.
Japanese Laid-open Patent Publication No. JP 2012-47951 A discloses a configuration in which an optical sensor is arranged in proximity to an optical path between a rotating fluorescent plate on which light emitted from a fixed light source is incident and a liquid crystal light modulator on which the light emitted from the rotating fluorescent plate is incident for controlling the fixed light source or the liquid crystal light modulator according to a detection result of the optical sensor.
In a projecting device in which a reflective light modulator is used, a part of light reflected by the reflective light modulator is transmitted according to image data through a reflective polarization plate to return to a light source. Therefore, an optical sensor arranged in proximity to an optical path between the light source and the reflective light modulator detects the light returning from the reflective light modulator to the light source together with the light emitted from the light source. Therefore, when the reflective light modulator is used, there is a problem that it is difficult to correctly detect a light amount of the light from the light source.